WASHINGTON — Medicare’s finances are looking brighter, the government said this morning. The program’s giant hospital trust fund won’t be exhausted until 2030 — four years later than last year’s estimate. Meanwhile, Social Security’s massive retirement program will remain solvent until 2034, officials say, although disability benefits are in more immediate danger. The disability trust fund now is projected to run dry in 2016, unless Congress acts. At that point, the program will collect enough payroll taxes to pay only 81 percent of benefits. The trustees who oversee Social Security and Medicare issued their annual report today on the financial health of the government’s two largest benefit programs. The trustees project a 1.5 percent increase in monthly Social Security payments to beneficiaries for next year. That would be among the lowest since automatic adjustments were adopted in the 1970s. The increase is based on a government measure of inflation. Medicare’s Part B monthly premium for outpatient care is expected to remain unchanged for next year, at $104.90. Average premiums for prescription coverage are expected to increase by less than $2 a month. Social Security’s finances are relatively unchanged from a year ago. Medicare’s improved finances are largely due to a continuing slowdown in health care spending, the report said.